Robust biomolecule quantitation is central to biomarker based clinical diagnostics, driving the development of high throughput, low cost medical diagnostic devices based on a myriad of biosensing technologies. Chief among the many relevant performance metrics of these devices is the ability to quantitate extremely low abundance analytes, such as picograms per milliliter and less, in complex matrices and in a multiplexed format (Heath, J. R.; Davis, M. E. Annu. Rev. Med. 2008, 59, 251-265). Regardless of the specific architecture or transduction methodology, affinity-based biosensors face limitations imposed by the Langmuir binding isotherm, which defines the ratio of solution-phase analyte to surface-bound analyte, as determined by the affinity of the capture agent employed. FIG. 1. At low concentrations, the amount of bound analyte is directly proportional to the solution sample concentration, as shown in eq 1, where θeq is the equilibrium surface coverage, Kads is the equilibrium binding constant, and [C] is the solution-phase analyte concentration:
                              θ          eq                =                                            K              ads                        ⁡                          [              C              ]                                            1            +                                          K                ads                            ⁡                              [                C                ]                                                                        [        1        ]            
Even when using high-affinity capture agents, restrictions imposed by the Langmuir isotherm, which are further exacerbated by mass transport limitations for sensing elements with small geometric footprints, can result in only a few individual molecules being bound to the sensor surface (Squires, T. M.; Messinger, R. J.; Manalis, S. R. Nat. Biotechnol. 2008, 26, 417-426; Sheehan, P. E.; Whitman, L. J. Nano Lett. 2005, 5, 803-807). Efforts to circumvent these fundamental limitations, and thus improve detection limits, include both the development of nanostructured morphologies with increased surface areas, as well as the integration of signal enhancement schemes that boost the per target sensor response (Soleymani, L.; Fang, Z.; Lam, B.; Bin, X.; Vasilyeva, E.; Ross, A. J.; Sargent, E. H.; Kelley, S. O. ACS Nano 2011, 5, 3360-3366; Munge, B. S.; Coffey, A. L.; Doucette, J. M.; Somba, B. K.; Malhotra, R.; Patel, V.; Gutkind, J. S.; Rusling, J. F. Angew. Chem., Int. Ed. 2011, 50, 7915-7918). Nonetheless, there remains an unmet need to develop assays to detect and quantitate extremely low abundance analytes.